Re: Semi-good high speed spindle idea? - Proxxon collet chucks

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Chris Horne" <chris@s...>
wrote:

>
>
> Aha..
>
> >>>>"I took a light skim off the OD of the rest of the
> part while it was still in the lathe."
>
> In effect thats what i did when mounting the proxxon collet chuck

onto

> a shaft to fit a 6mm collet
>
> I guess for 8mm skate bearings if you were to be machining this in

the

> lathe then it would be best to start with the next size up stock and
> machine down the bearing seats also rather than start with 8mm and
> build in the runout of the chuck...
>
> Chris
>
>
> thats the bit that makes the difference

Yep, everything that needs to be concentric needs to be machined in
the same setup (if possible). And don't trust drills and reamers to
cut that true. Actually machine the surfaces. My collets in the lathe
have a little runout, so I never use a stock diameter for anything
that has to be true. I go oversize and cut a slight amount off the
OD's. That way the final parts are as true as the lathe bearings run,
not the chucks or collets.

I have a bunch of probably the same 8mm bearings you do, and use them
a lot. Preloaded, they seem to work great. I've make other spindles
using them and mounted small ball screw ends in them (all preloaded),
and always seem to get a 1/4 thou or less runout in the total
assemblies. That's been good enough for my purposes, so I really
haven't tried to get less.

Irby